1. Field of the Invention
The invention pertains generally to heavy duty, commercial storage racks, usually found in warehouses, distribution centers, and home improvement centers. More specifically, the invention relates to a locking pin mechanism for automatically or manually locking beams, posts, or other structural members which comprise rack or shelf systems.
2. Description Of The Prior Art
Prior art racks for storing palletized goods typically include a plurality of horizontal beams, upright posts, and plywood sheets. Pairs of the horizontal beams are spaced in vertical relation and interconnected at each end to a respective upright post. Horizontal and angled cross braces are usually provided between the end pairs of upright posts, for additional rigidity. The paired beams are parallel and horizontally spaced so they can support a plywood sheet, forming a rack or shelf upon which items pan be stored and displayed.
For example, in U.S. Pat. No. 4,972,783, a structure for adjustable shelving is shown. U-shaped uprights include a plurality of apertures spaced in vertical relation along their sides. Each end of a horizontal beam has a J-shaped cap, adapted to engage one side of the upright. Each beam end also includes at least one spring-loaded shotpin, for engaging a selected aperture in an upright. Once all the beams are engaged with respective uprights at the selected heights, a shelf is placed over and supported by each corresponding pair of beams.
Another popular pallet rack system includes rows of key-hole shaped slots in the uprights. For engaging the uprights, the beams include right-angled endplates, typically fitted with a number of headed lugs. The lugs are sized initially to pass through a larger, upper portion of the key-hole. Then, the beam and the associated endplate are urged downwardly, and the lugs nest within a smaller, lower portion of their respective key-holes. The lower portion of the key-hole engages abutting surfaces of the lug head, preventing outward movement of the lug and the attached beam.
However, if the aforementioned rack system lacks an auxiliary beam locking mechanism, assembly of the rack can be difficult. During assembly, the pallet structure is awkward to handle, and somewhat flimsy until a number of beams and uprights are connected. Because there are no downward, loading forces on the beams, the lugs may inadvertently be dislodged from the key-hole, causing unexpected separation of the beams and uprights. And, even after the rack is fully assembled, safety issues can arise. If upward, vertical forces are applied to the beam, the lugs can easily be urged out of the key-holes, disengaging the beam and the upright. For example, serious accidents have occurred when loads have been moved onto or off of the rack, and a forklift operator accidentally lifts a beam out of engagement with its respective upright.
An example of a beam locking mechanism is shown in U.S. Pat. No. 4,262,809, issued to Mc Connell. This reference teaches a "loadlock" assembly, in each end of the beam of a pallet rack structure. The loadlock includes a right-angled bolt, slidable within an elongated, contoured slot in the sidewall of an end of the beam. The bolt carries a retainer, made of spring metal, which projects through the contoured slot. The bolt may selectively moved into three different positions: a shipping position; a loading position; and, a locked position.
However, the slidable resistance of the bolt, retainer, and slot assembly in Mc Connell is such that a hammer or other tool is necessary to move the bolt from a locked position to a shipping position. In fact, the relative difficulty of moving the bolt is identified as an advantage of the locking mechanism. Moreover, the components and structures of Mc Connell's loadlock mechanism are relatively expensive to manufacture and difficult to assemble.
The need still exists, then, for a locking mechanism which is simple and inexpensive to manufacture and assemble, yet effective and positive in preventing accidental and unexpected separations of structural members in rack and shelf systems.
The need also exists for a locking mechanism between structural members which can be manipulated easily by hand, from an enabled mode to a disabled mode.
The need also exists for a locking mechanism between structural members which can be manipulated easily by hand, from a locked position to an unlocked position.
The need further exists for a locking mechanism which will automatically extend into a locked position, during assembly of structural members such as beam and upright components comprising a pallet rack system.